Epilepsy - Exams and Tests
Making the correct diagnosis is vital
to identifying the appropriate treatment to control
epilepsy can be quite difficult. When you consult a
doctor after you or your child has had unexplained seizures, you and the doctor
will work together to answer three questions:
- Was the event a seizure, or was it something that looked like a seizure? Several conditions can appear
to be seizures but are not in fact seizures. (These might include
migraine headaches, muscle twitches or
tics, sleep disorders, or
psychogenic seizures.) Taking antiepileptic medicines
to treat nonepileptic seizures can expose you or your child to unnecessary
- If you are having seizures, are the seizures caused by epilepsy? Not everyone who has a seizure has epilepsy. The
seizure may have been caused by something else (such as fever, certain
electrolyte imbalance, or inhaling fumes). Taking
antiepileptic medicines when you do not have epilepsy may put you at
unnecessary risk from possible side effects.
- If you have or may have epilepsy, what types of seizures are you having? The
different types of
epileptic seizures (partial and generalized) are not
treated in the same way or with the same medicines. For example, some medicines
that control complex partial seizures may make
absence seizures worse.
A physical exam and detailed
medical history often provide the best clues as to
whether you have epilepsy and what type of epilepsy and seizures you have.
Discussing what happens to you just before, during, and right after a seizure
can help the doctor make a diagnosis.
Your doctor may want to
rule out other possible causes for the seizures with other laboratory
tests, which may include:
- Complete blood count (CBC) to check
for infection, and blood chemistry tests to check for abnormal
electrolyte levels (such as magnesium, sodium, and
calcium), signs of kidney or liver malfunction, and other common
- Lumbar puncture (sometimes called a
spinal tap), which is an analysis of spinal fluid evaluated to rule out
infections, such as meningitis and encephalitis.
- Toxicology screen, which examines blood, urine, or
hair to look for poisons, illegal drugs, or other toxins.
The most useful test in
support of a diagnosis of epilepsy is an
electroencephalogram (EEG). A computer records your
brain's electrical patterns as wavy lines. If you have epilepsy, the EEG may
show abnormal spikes or waves in your brain's electrical activity patterns.
Different types of epilepsy cause different patterns. But an
EEG is limited in its ability to diagnose epilepsy. And many people with
epilepsy have normal EEGs in between seizures.
Imaging tests (MRI and CT)
Magnetic resonance imaging (MRI) and
computed tomography (CT) are imaging tests that allow
a doctor to view the brain and evaluate the cause and location of
a possible source of epilepsy within the brain. The scans can reveal scar
tissue, tumors, or structural problems in the brain that may be the cause of
seizures or epilepsy. MRI is the more helpful test in most cases. Imaging tests
may not be done after a first seizure, but they are recommended in
many situations (such as after a first seizure in adults or after a head injury).